2.1.1 Remove Duplicates from Sorted Array

问题

答案

#include <stdio.h>#include <stdlib.h>//打印数组void print_array(int *pArry, int len){    int i;    for (i = 0; i < len; i++) {        printf("%08x, ", *(pArry+i));        if (!((i+1)%4))            printf("\n");    }    printf("\n");}//生成已排序的数组void get_sorted_array(int *pArry, int len){    int i, j, k;    i = 1;    j = 0;    while (j < len) {        for (k = 0; k < i; k++)            pArry[k+j] = i;        j += i;        i++;    }}//移除数组中重复元素int remove_duplicates(int *pArry, int len){    int old_idx; //save last valid data in array, also new length of array        int new_idx; //save next non-duplicate data in array    old_idx = 0;    new_idx = 1;    while (new_idx < len) {        while (pArry[old_idx] == pArry[new_idx]) {            new_idx++;        }        if (old_idx != new_idx-1) {            old_idx++;            pArry[old_idx] = pArry[new_idx];        }        new_idx++;    }    return old_idx;}int main(void){    int *pArray;    int len;    printf("please input len:");    scanf("%d", &len);    pArray = (int *)malloc(len * sizeof(int));    get_sorted_array(pArray, len);    printf("before sorted:\n");    print_array(pArray, len);    len = remove_duplicates(pArray, len);    printf("\n");    printf("after sorted:\n");    print_array(pArray, len);    return 0;}

结果

分析
看了其它代码的实现，发现自己的代码不够简洁，所以做了些修改。

//其他人的代码//优点：代码简洁，需注意先自增再赋值//缺点：赋值次数较多int remove_duplicates_2(int *pArry, int len){    int i, idx;    idx = 0;    for (i = 1; i < len; i++) {        if (pArry[idx] != pArry[i])            pArry[++idx] = pArry[i];    }    return idx+1;}//自己优化后的代码//优点：代码简洁，需注意循环里每次只执行一个分支，用外层for循环代替了原来内层的while循环//缺点：无int remove_duplicates_3(int *pArry, int len){    int old_idx;    int new_idx;    for (old_idx = 0, new_idx = 1; new_idx < len; new_idx++) {        if (pArry[old_idx] == pArry[new_idx]) {            new_idx++;        }        else if (old_idx != new_idx-1) {            pArry[++old_idx] = pArry[new_idx];        }    }    return old_idx+1;}